Weapon active hazard mitigation method

ABSTRACT

A mitigation control system, for performing an active hazard mitigation method, is arranged in an environment containing an energetic material and includes an abnormal temperature sensor for detecting an abnormal temperature of the environment, a power source that is mechanically actuated by the abnormal temperature sensor when the abnormal temperature exceeds a predetermined abnormal temperature threshold, a mitigation controller that is actuated by the power source, and a plurality of local temperature sensors that are communicatively coupled to the mitigation controller and are arranged for detecting critical temperatures in specific regions of the environment. The mitigation controller executes a mitigation action when one of the critical temperatures exceeds a predetermined critical temperature threshold for the corresponding specific region.

This application is a divisional application of application Ser. No.16/716,552, filed Dec. 17, 2019, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The invention relates to a system and method for mitigating hazardousreactions when an environment containing an energetic material issubject to unplanned stimuli.

DESCRIPTION OF THE RELATED ART

Various applications may use energetic materials that are able torelease stored chemical energy. Examples of environments in whichenergetic materials are contained include weapon systems, such as cruisemissiles, and other transportation systems. During operation, such asduring execution of a mission, the environment containing the energeticmaterial may be subject to external and unplanned stimuli. For example,a cruise missile may be subject to a thermal threat when the weapon isunexpectedly impacted. When subject to the unplanned stimuli, a violentenergetic response from the energetic material in the environment mayoccur. The responses may cause collateral damage to weapon platforms,logistic systems, and personnel.

In military applications, insensitive munitions are required to havesafety measures when subject to unplanned stimuli. The requirements arebased upon a military standard MIL-STD-2105D which requires theenergetic response to have an ejecta kinetic energy that is less than 20joules (15 foot-pound force). For example, the requirements may includemeeting STANAG 4439 standards. Different types of MIL-STD-2105Denergetic responses include six different types of mitigation reactionsthat have different levels of violence. The most violent reactionsinclude a Type I detonation reaction during which energetic material ofthe munition system is consumed in a supersonic decomposition, a Type IIpartial detonation reaction during which some of the energetic materialis consumed in the supersonic decomposition, a Type III explosionreaction during which sub-sonic decomposition of energetic material andextensive fragmentation occurs, and a Type IV deflagration reactionduring which ignition and burning of confined energetic materialsoccurs.

The least violent reactions include a Type V burning reaction duringwhich the energetic material ignites and burns non-propulsively, and aType VI no reaction during which any reaction self-extinguishesimmediately upon removal of the external stimuli. The less violent TypeV and VI reaction types are preferable to the more violent reactions.

Providing mitigation in some environments, such as in integrated weaponsystems, is difficult due to the complexity of providing a mitigationsolution for each sub-assembly which contains unique components and hasdifferent characteristics relative to the other sub-assemblies. Someintegrated systems include sub-assemblies with both solid and liquidenergetic materials that require different mitigation techniques. Launchsystems in which the weapon is stored in a canister also presentchallenges in mitigation due to the impact of the canister whendetecting thermal threats. For example, the canister may prohibit orhinder the activation of a subsystem mitigation system.

SUMMARY OF THE INVENTION

The mitigation control system described herein is configured to minimizethe probability of an uncontrolled initiation and to minimize theseverity of subsequent collateral damage to weapon platforms, logisticsystems and personnel due to accidental threats. The mitigation controlsystem includes a hybrid sensor system having both passive and activesensors that are used to detect thermal threats in an environmentcontaining an energetic material. The mitigation control system uses acontroller that configures and validates a network of sensors, such astemperature sensors, pressure sensors, or other suitable sensors, toanalyze the environment. If the analysis indicates a possible threat,the system will send a notification signal, continue to monitor, andpredict when a mitigation event is likely to occur. If the analysisindicates that mitigation is necessary, a power supply is activated anda fire pulse may be generated to initiate a mitigation energetic, suchas a linear shape charge.

The sensors are used in conjunction with a mitigation controller that isconfigured to execute a specific mitigation action or technique for aspecific region within the environment. The passive temperature sensoris used to detect an abnormal temperature of the environment. When theabnormal temperature exceeds a predetermined threshold indicating thatthe environment is subject to unplanned external stimuli causing athermal threat, the abnormal temperature sensor mechanically triggers apower source. The environment containing the energetic material may be atransportation vehicle, such as an air vehicle or cruise missile, andthe passive temperature sensor detects the abnormal temperature outsideof the vehicle body. In a launch system in which the missile is arrangedin a canister, the passive temperature sensor may be mounted to thecanister for detecting the abnormal temperature around the canister.

The power source may include a thermal battery, a capacitor, an externalpower source such as the platform, or any other suitable power source.The mitigation controller is subsequently electrically actuated via thepower source which may supply a current to the mitigation controller totransition the mitigation controller from a normal sleep mode to a poweron mode. The mitigation controller is communicatively coupled with aplurality of local sensors that are arranged at different regions withinthe environment. For example, the sensors may be temperature or pressuresensors. In the air vehicle body, the local temperature sensors arearranged in different sub-assemblies that are integrated to form themain air vehicle body. The local temperature sensors are configured todetect the temperature in each region or sub-assembly.

When a detected temperature exceeds a predetermined critical temperaturethreshold for the specific region or sub-assembly, the mitigationcontroller is configured to initiate a mitigation action or techniquecorresponding to the region in which the critical temperature has beenreached. An active cell battery or any other suitable method forreceiving anti-radiation missile power powers the control system fromthe initial trigger temperature to initiation. The active cell batterypowers a fire pulse and provides sustain logic after initiation. Themitigation controller includes a power management subsystem toconstantly monitor the power. The power monitoring is used to ensurethat there is enough power to activate a firing detonator or initiator,or other intended function.

The mitigation controller communicates with a plurality of mitigationsubcontrollers that are each arranged in the different regions andconfigured to execute the specific mitigation action or techniquecorresponding to the region. The mitigation action or technique may bedifferent for each region and the mitigation action or technique may bepassive or active. Examples of mitigation actions or techniques includeat least one of venting, shielding, painting, using shear bolts orstress raisers, softening a component within the environment, ignitingthe energetic material below an ignition temperature for the energeticmaterial, using a thermal initiated venting system for fuel release orcomponent cutting, performing a controlled burn, controlling a locationof ignition within the environment, or perform an early ignition of theenergetic material. A cruise missile may include warhead, fuel tank, jetengine, and booster sub-assemblies that each have a separate mitigationsubcontroller. The mitigation subcontroller for the fuel tanksub-assembly may execute a fuel release sequence that enables acontrolled burn without increasing the pressure inside the cruisemissile body, whereas the mitigation subcontrollers for the warheadsub-assembly and the rocket motor sub-assembly may each perform ventingor a cutting sequence for the warhead or motor to reduce violence tothermal insensitive munition threats.

The mitigation control system is advantageous in ensuring effectivemitigation by providing sub-assembly compliance using a system levelcontrol unit. In military applications, the system may be used toachieve military standard MIL-STD-2105D Type V or Type VI energeticresponses that are less violent as compared with other possibleenergetic responses to unplanned stimuli. Using both passive and activetemperature sensors also enables the mitigation controller to rest in anunpowered or low powered state until the thermostat-type passive sensordetects a thermal threat. Still another advantage of the mitigationcontrol system is implementing the mitigation control system in a launchsystem in which the mitigation actions or techniques for thesub-assemblies will not be hindered when the missile is arranged in acanister.

According to an aspect of the invention, a mitigation control systemincludes passive and active sensors.

According to an aspect of the invention, a mitigation control systemincludes an active hazard mitigation unit.

According to an aspect of the invention, a mitigation control systemincludes mitigation subcontrollers that are each arranged in thedifferent regions and configured to execute the specific mitigationaction or technique corresponding to the region.

According to an aspect of the invention, a mitigation control system isarranged in an environment containing an energetic material and themitigation control system includes an abnormal temperature sensor fordetecting an abnormal temperature of the environment, a power sourcethat is mechanically actuated by the abnormal temperature sensor whenthe detected temperature exceeds a predetermined temperature threshold,a mitigation controller that is electrically actuated by the powersource, and a plurality of local temperature sensors, or otherenvironmental sensors, that are communicatively coupled to themitigation controller and are arranged for detecting criticaltemperatures in specific regions of the environment, wherein themitigation controller initiates a mitigation action when one of thecritical temperatures in a corresponding one of the specific regionsexceeds a predetermined critical temperature threshold.

According to an embodiment of any paragraph(s) of this summary, theabnormal temperature sensor is a passive sensor and the plurality oflocal temperature sensors are active sensors.

According to an embodiment of any paragraph(s) of this summary, thepower source includes a self-contained battery or power from an externalsource.

According to an embodiment of any paragraph(s) of this summary, themitigation controller has a sleep mode and the thermal battery isconfigured to supply current to the mitigation controller fortransitioning the mitigation controller to a power on mode from thesleep mode.

According to an embodiment of any paragraph(s) of this summary, themitigation control system includes a plurality of mitigationsubcontrollers that are each arranged in different specific regions ofthe environment and configured to execute a predetermined mitigationaction or technique for the corresponding specific region.

According to an embodiment of any paragraph(s) of this summary, themitigation action or technique is passive or active.

According to an embodiment of any paragraph(s) of this summary, thepassive action or technique includes at least one of venting, shielding,painting, using shear bolts or stress raisers, and softening a componentwithin the environment.

According to an embodiment of any paragraph(s) of this summary, theactive action or technique includes at least one of igniting theenergetic material below an ignition temperature for the energeticmaterial, using a thermal initiated venting system for fuel release orcomponent cutting, performing a controlled burn, controlling a locationof ignition within the environment, performing an early ignition of theenergetic material, and weakening a component within the environment.

According to an embodiment of any paragraph(s) of this summary, theenvironment is a transportation vehicle.

According to another aspect of the invention, an air vehicle containingan energetic material includes a main body formed of a plurality ofintegrated sub-assemblies, and a mitigation control system that isarranged in the main body and includes a passive temperature sensor fordetecting an abnormal temperature of the main body, a power source thatis mechanically actuated by the passive temperature sensor when thedetected abnormal temperature exceeds a predetermined abnormaltemperature threshold, a mitigation controller that is electricallyactuated by the power source, and a plurality of active temperaturesensors that are communicatively coupled to the mitigation controllerand are each embedded in a different one of the sub-assemblies fordetecting a critical temperature of the corresponding sub-assembly. Themitigation controller executes a mitigation action or technique when thedetected critical temperature exceeds a predetermined criticaltemperature threshold for the corresponding sub-assembly.

According to an embodiment of any paragraph(s) of this summary, thepower source includes a self-contained battery or power from an externalsource.

According to an embodiment of any paragraph(s) of this summary, the airvehicle includes a plurality of mitigation subcontrollers that arearranged in different sub-assemblies and configured to execute apredetermined mitigation action for the corresponding sub-assembly.

According to an embodiment of any paragraph(s) of this summary, themitigation action or technique is passive or active.

According to an embodiment of any paragraph(s) of this summary, thepassive action or technique includes at least one of venting, shielding,painting, using shear bolts or stress raisers, and softening a componentwithin the air vehicle.

According to an embodiment of any paragraph(s) of this summary, theactive action or technique includes at least one of igniting theenergetic material below an ignition temperature for the energeticmaterial, using a thermal initiated venting system for fuel release orcomponent cutting, performing a controlled burn, controlling a locationof ignition within the air vehicle, performing an early ignition of theenergetic material, and weakening a component within the air vehicle.

According to an embodiment of any paragraph(s) of this summary, the airvehicle is a cruise missile having energetic materials that are solidand/or liquid.

According to an embodiment of any paragraph(s) of this summary, theplurality of integrated sub-assemblies include a warhead, a fuel tank, ajet engine, and a booster.

According to an embodiment of any paragraph(s) of this summary, themitigation action or technique includes an energetic response that is aMIL-STD-2105D military standard Type V burning reaction response or aType VI no reaction response.

According to an embodiment of any paragraph(s) of this summary, the airvehicle is arranged in a launch system having a canister in which theair vehicle is stored, and the at least one passive temperature sensoris mounted to the canister.

According to still another aspect of the invention, a method formitigating an active hazard in an air vehicle containing an energeticmaterial includes detecting an abnormal temperature of the air vehicle,mechanically actuating a power source when the detected temperatureexceeds a predetermined temperature threshold, electrically actuating amitigation controller after the power source is actuated, detecting acritical temperature in separate sub-assemblies that are integrated toform the air vehicle after the mitigation controller is actuated, andexecuting a mitigation action or technique in at least one of thedifferent sub-assemblies using the mitigation controller when thecritical temperature in the corresponding sub-assembly exceeds apredetermined critical temperature threshold.

To the accomplishment of the foregoing and related ends, the inventioncomprises the features hereinafter fully described and particularlypointed out in the claims. The following description and the annexeddrawings set forth in detail certain illustrative embodiments of theinvention. These embodiments are indicative, however, of but a few ofthe various ways in which the principles of the invention may beemployed. Other objects, advantages and novel features of the inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

The annexed drawings, which are not necessarily to scale, show variousaspects of the invention.

FIG. 1 shows a mitigation control system for an environment containingan energetic material.

FIG. 2 shows a cruise missile having sub-assemblies that are integratedto form the cruise missile body.

FIG. 3 shows a launch system in which the cruise missile of FIG. 2 isarranged in a canister.

FIG. 4 shows the mitigation control system of FIG. 1 being implementedin the launch system of FIG. 3 .

FIG. 5 shows a flow chart for a method for mitigating an active hazardin an air vehicle containing an energetic material using the mitigationcontrol system of FIG. 1 .

DETAILED DESCRIPTION

The principles described herein have application in any environment thatcontains an energetic material and requires a mitigation action ortechnique to control a reaction of the energetic material when subjectto a thermal threat. Energetic materials include materials that are ableto release stored chemical energy. Exemplary materials includeexplosives, pyrotechnic compositions, propellants, and other fuel oroxidizer mixtures. Suitable platforms that may include an energeticmaterial and a mitigation control system for the energetic materialinclude air, land, space, and sea vehicles in defense applications orother military applications. The platform may be stationary or moving.Manned or unmanned platforms may be suitable. Weapons including cruisemissiles are suitable platforms. Other exemplary applications includetransportation systems and vehicles, communication-type applications,and laboratory environments.

Referring first to FIG. 1 , a mitigation control system 10 is shown. Themitigation control system 10 is arranged in an environment 12 containingan energetic material. The environment 12 may be an enclosure and anysuitable platform may include the environment 12, such as atransportation vehicle. Different compartments or regions 14, 16 mayform the environment 12 or be a part of the environment 12. The regions14, 16 may be separated relative to each other and enclosed within theenvironment 12. In exemplary applications, the regions 14, 16 may beintegrated or interact with each other to form the entire environment.Each region 14, 16 is different and includes a corresponding componentor a set of components that are configured to perform a function for thespecific region 14, 16. For example, in an application in which theenvironment 12 is an air vehicle, the regions 14, 16 may besub-assemblies of the air vehicle that are integrated to form the mainvehicle body. Exemplary sub-assemblies for an air vehicle include a fueltank body and a jet engine body that contain a fuel tank and a jetengine, respectively, that are integrated for operation of the airvehicle.

The mitigation control system 10 includes at least one abnormaltemperature sensor 18 for sensing an abnormal temperature of theenvironment 12. The abnormal temperature may be a temperature within theenvironment 12 or directly outside the enclosure of the environment 12.The abnormal temperature sensor 18 is a passive sensor and includes amechanical activation element to determine if a temperature in theenvironment 12 exceeds a predetermined temperature threshold thatcorresponds to an energetic hazard onset. Any suitable thermostat-typeof passive sensor may be used and the sensor may include a thermalswitch, a bimetallic thermometer, or any other suitable thermometer. Theabnormal temperature sensor 18 may be mounted within the environment 12and the arrangement of the abnormal temperature sensor 18 may bedependent on the environment 12 and the enclosure for the environment12. A plurality of abnormal temperature sensors 18 may be provided andarranged at different locations around the environment 12. Using thepassive abnormal temperature sensor 18 is advantageous in that thesensor does not require an external power source and is only used todetect when the abnormal temperature exceeds the threshold, as comparedwith the more complex arrangement of an active sensor that would requirean external power source. Accordingly, the mitigation control system 10may remain in an unpowered or low powered state until the passiveabnormal temperature sensor 18 detects the thermal threat.

The mitigation control system 10 further includes a power source 20 thatis coupled to the abnormal temperature sensor 18 and is mechanicallyactivated by the mechanical activation element of the abnormaltemperature sensor 18 when the detected abnormal temperature exceeds thepredetermined threshold corresponding to thermal threats. The powersource 20 may include a thermal battery 22 having an initiation elementthat is mechanically activated by the activation element of the abnormaltemperature sensor 18. If the mitigation control system 10 determinesthat mitigation is necessary, the power source 20 is activated and afire pulse may be generated to initiate a mitigation energetic, such asa linear shape charge. For example, a thermal batter initiator may besquibbed. Any other suitable power source may be used, includingcapacitors or other external power sources, such as power from theplatform itself.

A mitigation controller or an active hazard mitigation unit (AHMU) 24 iscommunicatively coupled to the power source 20 and is electricallyactuated by the power source 20, subsequently to the actuation of thepower source 20. The AHMU 24 may be configured to monitor. The powersource 20 may be electrically coupled to the AHMU 24 for supplyingcurrent to the AHMU 24 to actuate the AHMU 24. The AHMU 24 may have bein a sleep or low power mode prior to receiving the current which wakesup the AHMU 24 and transitions the AHMU 24 from the sleep mode into apower on mode. The mitigation controller may include a power managementsubsystem 24 a to constantly monitor the power. The mitigationcontroller includes a power management subsystem to constantly monitorthe power. The power monitoring is used to ensure that there is enoughpower to activate a firing detonator or initiator, or other intendedfunction.

A local temperature network or sensor array is formed of a plurality oflocal temperature sensors 26, 28 that are each arranged in acorresponding one of the regions 14, 16 of the environment 12 andcommunicatively coupled with the AHMU 24. The temperature sensors mayalso include other environmental sensors. The local temperature sensors26, 28 are active sensors that detect local temperatures in the regions14, 16 of the environment 12 and send data corresponding to the detectedtemperatures back to the AHMU 24 which determines whether the detectedtemperatures exceed a predetermined critical temperature for the region14, 16. Each region 14, 16 may have a different critical temperaturethat is dependent on the temperature at which self-heating reactions mayoccur for the specific region 14, 16.

Each region 14, 16 may have a mitigation subcontroller 30, 32 that isarranged in the region 14, 16 and configured to execute a specificmitigation action or technique for the corresponding region 14, 16. Eachmitigation subcontroller 30, 32 may be arranged to execute a differentmitigation action or technique which is passive or active. A passivemitigation action of technique includes any mitigation action ortechnique that does not cause a response from the energetic material.For example, a passive mitigation action or technique includes an actionthat does not contain energetic substance or generate any explosiveeffect. An active mitigation action or technique includes any actioncausing a thermal or explosive effect to cause an energetic response.Examples of suitable passive mitigation actions or techniques includeproviding venting paths in the environment 12, shielding components,painting a component with a protective coating, using shear bolts orstress raisers to localize stress in a specific area, or softening acomponent within the region 14, 16. Examples of suitable activemitigation actions or techniques include igniting the energetic materialbelow an ignition temperature for the energetic material, using athermal initiated venting system for fuel release or component cutting,performing a controlled burn, controlling a location of ignition withinthe environment 12, performing an early ignition of the energeticmaterial, and weakening a component within the environment 12. Manyother mitigation actions or techniques may be executed.

The AHMU 24 may be entirely implemented in any suitable hardware and maybe autonomous. The AHMU 24 is configured to monitor. If the analysisindicates a possible threat, the system will send a notification signal,continue to monitor, and predict when a mitigation event is likely tooccur. Fuse-based configurable logic may be suitable for implementingthe AHMU 24. The AHMU 24 prediction and mitigation of hazards is basedon collected inputs over time, and the AHMU 24 may be configured todetermine the appropriate outcome based on the collected data. Thedetermination of a time and/or a thermal threshold to initiate anon-reversible mitigation sequence may be configurable. The AHMU 24 maybe configured to adapt to the thermal environment and manage the powersources to minimize potential hazards. For example, if the threat is notincreasing, the AHMU 24 is configured to continue to monitor at a slowerrate.

A memory 34 may be arranged in the AHMU 24 and configured to store datapertaining to different mitigation actions that correspond to thedetected critical temperature for the corresponding region 14, 16. Thememory 34 may also store an algorithm or executable commands pertainingto assessing the data received from the local temperature sensors 26, 28and determining the appropriate mitigation action based on the detecteddata. When the AHMU 24 receives data from the local temperature sensors26, 28, the AHMU 24 is configured to communicate with the mitigationsubcontrollers 30, 32 to initiate the mitigation action.

Referring now to FIGS. 2 and 3 , an exemplary air vehicle 36 is shown.The air vehicle 36 may be a suitable environment 12 for the mitigationcontrol system 10, as shown in FIG. 1 . In an exemplary embodiment, theair vehicle 36 may be a weapon such as a cruise missile. A plurality ofsub-assemblies 38, 40, 42, 44 are integrated with each other to form amain body 46 of the air vehicle 36. In an exemplary configuration of theair vehicle 36, the sub-assemblies 38, 40, 42, 44 may include a warheadmodule 38, a fuel tank module 40, a jet engine module 42, and a boostermodule 44. Each sub-assembly 38, 40, 42, 44 may include a housing forcomponents that perform different functions for the air vehicle 36.Other suitable configurations of the air vehicle 36 may includedifferent sub-assemblies.

Each sub-assembly 38, 40, 42, 44 includes unique components relative tothe other sub-assemblies 38, 40, 42, 44 and the sub-assemblies 38, 40,42, 44 may each include solid and/or liquid energetic materials. Thewarhead module 38 may include a unitary or tandem warhead system and thejet engine module 42 may include a turbo jet engine. The fuel tankmodule 40 may contain fuel having a mitigation requirement in which thefuel threat must be converted to an open thermal source rather than afuel-air explosive. FIG. 3 shows a launch system 48 for the air vehicle36 that includes a canister 50 in which the air vehicle 36 is storedprior to release. In the launch system 48, the canister 50 may be theenvironment 12 which includes the mitigation control system 10.

FIG. 4 shows the mitigation control system 10 being implemented in thelaunch system 48. The abnormal temperature sensor 18 of the mitigationcontrol system 10 is arranged on the canister 50 to detect the abnormaltemperature of the environment surrounding the canister 50. Any suitablemounting mechanism may be suitable. The abnormal temperature sensor 18may be embedded within a wall or housing of the canister 50. In otherexemplary embodiments, the abnormal temperature sensor 18 may bearranged on the outer side of the main body 46 of the air vehicle 36 orat a location inside the canister 50. The arrangement of the abnormaltemperature sensor 18 is dependent on the application.

When the abnormal temperature exceeds a predetermined abnormaltemperature threshold indicating that the air vehicle 36 is subject toan energetic hazard, the abnormal temperature sensor 18 is configured tomechanically trigger the thermal battery 22. Upon actuation of thethermal battery 22, the thermal battery 22 supplies current to the AHMU24 which may be in a sleep mode prior to receiving current from thethermal battery 22. The AHMU 24 is then actuated and queries the localtemperature sensor network including the plurality of local temperaturesensors 26, 28, 52, 54, 56 that are each communicatively coupled withthe AHMU 24. The local temperature sensors 26, 28, 52, 54, 56 arearranged at different locations within the integrated sub-assemblies 38,40, 42, 44 of the air vehicle 36. The arrangement of the localtemperature sensors 26, 28, 52, 54, 56 may be dependent on thearrangement of the sub-assemblies 38, 40, 42, 44 and the sensors may bearranged within the module housings or directly outside the modulehousings.

In an exemplary embodiment of the local temperature sensor network orsensor array, some of the local temperature sensors 26, 28 may bearranged in the warhead module 38 and spaced relative to each other. Oneof the local temperature sensors 26 may be arranged proximate a nose end58 of the air vehicle 36 and spaced from a payload 60 contained in thewarhead module 38. The other local temperature sensor 28 may be arrangedon the payload 60 or proximate the payload 60. The fuel tank module 40may include the local temperature sensor 52, the jet engine module 42may include the local temperature sensor 54, and the booster module 44may include the local temperature sensor 56. The local temperaturesensors 52, 54, 56 may be arranged proximate a specific component or thetemperature sensors may be arranged at any location in the modulehousing. For example, the temperature sensor 52 may be arranged in aliquid fuel region of the fuel tank module 40 and the temperature sensor54 may be arranged in a rocket motor of the booster module 44.

When one of the local temperature sensors 26, 28, 52, 54, 56 detects atemperature in the corresponding sub-assembly 38, 40, 42, 44 thatexceeds a critical temperature for the sub-assembly 38, 40, 42, 44, i.e.when the temperature is critical to a self-heating reaction, the AHMU 24activates the mitigation subcontrollers 30, 32, 62 that are arranged inthe sub-assemblies 38, 40, 42, 44, respectively. The mitigationsubcontrollers 30, 32, 62 then execute the suitable mitigation actionfor the corresponding sub-assembly 38, 40, 42, 44. The AHMU 24 may beconfigured to activate any suitable ignitor of the mitigationsubcontrollers 30, 32, 62.

In an exemplary embodiment of the mitigation subcontrollers 30, 32, 62,the mitigation subcontroller 32 for the fuel tank module 40 may beconfigured to execute a multi-step sequence in which the fuel isreleased by providing a controlled burn without increasing pressureinside the air vehicle 36. The fuel release sequence may be a thermalinitiated venting system (TIVS) type of fuel release. Using themitigation control system 10 is advantageous in that the finaltriggering sequence for the controlled burn does not occur until thelocal temperature sensor 52 detects the hazardous threat in the fueltank module 40, enabling an active burn control.

The mitigation subcontrollers 30, 62 for the warhead module 38 and thebooster module 44 may be configured to perform venting for thecorresponding sub-assembly 38, 44 to enable clearing of the energeticmaterial from the air vehicle 36. Another mitigation action for thewarhead module 38 or the booster module 44 may include taking apart thepayload 60 or the rocket motor, such as a TIVS type of motor or warheadcutting. Still another mitigation action that is suitable for any of thesub-assemblies 38, 40, 42, 44 includes any action that enables theenergetic material to burn non-propulsively, similar to the burning of acandle. Any suitable passive or active mitigation action may besuitable.

Using the mitigation control system 10 is particularly advantageous inintegrated systems such as a cruise missile in that the mitigationcontrol system 10 enables compliance of each individual sub-assembly ata higher system level. The mitigation control system is configured tominimize the probability of an uncontrolled initiation and to minimizethe severity of subsequent collateral damage to weapon platforms,logistic systems and personnel due to accidental threats. The abnormaltemperature sensor 18 acts as a thermostat which enables the mitigationcontrol system 10 to conserve power until a thermal threat is detected.In contrast to conventional mitigation methods in which a canister mayimpact the thermal threat characteristics and prohibit subsystemmitigation techniques, the mitigation control system 10 described hereinensures mitigation at the subsystem level when the air vehicle 36 isarranged in the canister 50 of the launch system 48.

Using the mitigation control system 10 in the air vehicle or cruisemissile 36 is also advantageous in enabling the reactions to meet amilitary standard MIL-STD-2105D for energetic responses, which providesthat the energetic response must have an ejecta kinetic energy that isless than 20 joules (15 foot-pound force). For example, the requirementsmay include meeting STANAG 4439 standards. The hybrid passive and activesensor system enables containerized cruise missiles to effectivelybehave similarly to “wooden rounds” when subject to unplanned externalstimuli or thermal threats. The mitigation control system 10 enables aType V burning reaction or Type VI no reaction per the MIL-STD-2105Denergetic response requirements. The Type V burning reaction is thefifth least violent type of munition reaction, as compared with the TypeI detonation reaction, Type II partial detonation reaction, Type IIIexplosion reaction, and Type IV deflagration reaction. In the Type Vburning reaction, the energetic material ignites and burnsnon-propulsively. The Type VI no reaction is the least violent type ofmunition reaction in which any reaction self-extinguishes immediatelyupon removal of the unplanned external stimuli.

Referring now to FIG. 5 , a method 64 for mitigating an active hazard inthe air vehicle 36 of FIGS. 2-4 includes using the mitigation controlsystem 10 shown in FIGS. 1 and 4 . Step 66 of the method 64 includesdetecting the abnormal temperature of the air vehicle 36 and step 68includes mechanically actuating the power source 20 when the abnormaltemperature exceeds a predetermined abnormal temperature threshold. Step70 of the method 64 includes electrically actuating the AHMU 24 afterthe power source 20 is actuated. The thermal battery 22 may be actuatedby the abnormal temperature sensor 18 and may subsequently actuate theAHMU 24, such as by supplying current to wake up the AHMU 24 from asleep mode.

Step 72 of the method 64 includes detecting the critical temperature inthe separate sub-assemblies 38, 40, 42, 44 that are integrated to formthe air vehicle 36 after the AHMU 24 is actuated. The local temperaturesensors 26, 28, 52, 54, 56 may be used to detect a temperature in thecorresponding sub-assembly 38, 40, 42, 44 that exceeds a criticaltemperature for the sub-assembly 38, 40, 42, 44. Step 74 of the method64 includes executing a mitigation action in at least one of thedifferent sub-assemblies 38, 40, 42, 44 using a corresponding one of themitigation subcontrollers 30, 32, 62 when the critical temperature inthe corresponding sub-assembly 38, 40, 42, 44 exceeds the predeterminedcritical temperature threshold.

Although the invention has been shown and described with respect to acertain preferred embodiment or embodiments, it is obvious thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described elements (external components,assemblies, devices, compositions, etc.), the terms (including areference to a “means”) used to describe such elements are intended tocorrespond, unless otherwise indicated, to any element which performsthe specified function of the described element (i.e., that isfunctionally equivalent), even though not structurally equivalent to thedisclosed structure which performs the function in the hereinillustrated exemplary embodiment or embodiments of the invention. Inaddition, while a particular feature of the invention may have beendescribed above with respect to only one or more of several illustratedembodiments, such feature may be combined with one or more otherfeatures of the other embodiments, as may be desired and advantageousfor any given or particular application.

What is claimed is:
 1. A method for mitigating an active hazard in anair vehicle containing an energetic material, the method comprising:detecting an abnormal temperature of the air vehicle; mechanicallyactuating a power source when the detected temperature exceeds apredetermined temperature threshold; electrically actuating a mitigationcontroller after the power source is actuated; detecting a criticaltemperature in separate sub-assemblies that are integrated to form theair vehicle after the mitigation controller is actuated; and executing amitigation action or technique in at least one of the differentsub-assemblies using the mitigation controller when the criticaltemperature in the corresponding sub-assembly exceeds a predeterminedcritical temperature threshold.
 2. The method of claim 1, wherein thedetecting the abnormal temperature includes detecting the abnormaltemperature with a passive temperature sensor.
 3. The method of claim 1,wherein the detecting the abnormal temperature includes detecting theabnormal temperature in an environment around the air vehicle.
 4. Themethod of claim 1, wherein the detecting the critical temperatureincludes detecting the critical temperature in one or more activetemperature sensors.
 5. The method of claim 1, wherein the detecting thecritical temperature includes detecting the critical temperature in oneor more temperature sensors that correspond to respective of thedifferent sub-assemblies.
 6. The method of claim 1, wherein different ofthe sub-assemblies have different critical temperatures.
 7. The methodof claim 1, wherein the sub-assemblies have respective mitigationsubcontrollers; and wherein the executing the mitigation action ortechnique includes the mitigation subcontrollers of the at least one ofthe different sub-assemblies executing the mitigation action ortechnique for the corresponding of the at least one of the differentsub-assemblies.
 8. The method of claim 1, wherein the mitigation actionincludes mitigation of a hazard from an energetic material.
 9. Themethod of claim 1, wherein the mitigation action includes mitigation ofa hazard from an explosive.
 10. The method of claim 1, wherein themitigation action includes mitigation of a hazard from a pyrotechniccomposition.
 11. The method of claim 1, wherein the mitigation actionincludes mitigation of a hazard from a fuel and/or oxidizer.
 12. Themethod of claim 1, wherein the mitigation action includes a passivemitigation action.
 13. The method of claim 12, wherein the passivemitigation action includes at least one of venting, shielding, painting,using shear bolts or stress raisers, and softening a component within anenvironment of the air vehicle.
 14. The method of claim 1, wherein themitigation action includes an active mitigation action.
 15. The methodof claim 14, wherein the active mitigation action includes one or moreof igniting an energetic material below an ignition temperature for theenergetic material, using a thermal initiated venting system for fuelrelease or component cutting, performing a controlled burn, andcontrolling a location of ignition.
 16. The method of claim 1, whereinthe sub-assemblies include a warhead module.
 17. The method of claim 1,wherein the sub-assemblies include a fuel tank module.
 18. The method ofclaim 1, wherein the sub-assemblies include a jet engine module.
 19. Themethod of claim 1, wherein the sub-assemblies include a booster module.20. The method of claim 1, wherein the air vehicle is a cruise missile.